Capsule technology continues to be subject to development and improvements. In its basic form, standard containers for pharmaceuticals or other powdered, granular or liquid substances (generally referred to as telescope-type or two-piece capsules or hard capsules) include a tubular-shaped and/or cylindrically-shaped first part, namely a cap part, which is closed on one end and open on the other opposite end. A tightly fitting second part of similar shape, namely the body part, is of smaller diameter than the cap part and is typically telescopically engaged therein to form the overall dosage form or two-piece capsule. Similar capsule technology may be used to generate multi-compartment capsules.
Sealing of capsules of the above type has been implemented mainly to allow storing of liquids within such capsules and preventing leakage there through.
EP 0 116 743 A1, EP 0 116 744 A1 and EP 0 180 543 A1 exemplify methods and devices for sealing such capsules having hard shell coaxial cap and body parts which overlap when telescopically joined. The process employed comprises the steps of dipping batches of the capsules randomly oriented in mesh baskets or oriented with their cap parts upright into a sealing fluid making capillary action within the overlap of the cap and body parts or spraying the sealing fluid or steam thereof onto the seam of the overlap, removing the sealing fluid from the surface of the capsules by an air blower, and applying thermal energy to the capsules while conveying the baskets through a dryer. The documents disclose the use of a wide range of sealing fluids and specific temperatures and modes of application of thermal energy.
Other state of the art equipment and methods, as exemplified in U.S. Pat. No. 4,940,499B, include the application of a sealing liquid by a series of angled nozzles whilst respective capsules are maintained in an inverted (i.e. cap down) orientation to enable the sealing liquid to penetrate the circumferential gap (also referred to herein as cap/body interface) via the combined gravitational and wicking effects.
Furthermore, EP 1 072 245 A1 exemplifies a method for sealing telescopically joined capsules with coaxial body parts through subsequent application of a sealing liquid by the overlapping region at the joint between a cap and a body, the removal of excess sealing liquid, and the application of thermal energy for drying purposes. This document particularly describes the steps of applying a sealing liquid including a solvent uniformly to the external edge of the gap of a capsule to be sealed to form a liquid ring around the circumference of the capsule, removing excess sealing liquid from the exterior of the capsule and drying the capsule by applying thermal energy from outside while gently tumbling and conveying the capsule on a spiral path. Spray nozzles are used for individually applying the sealing liquid. The excess solution is removed from around the capsule by vacuum suction or air jets.
In order to address some of the problems of the prior art, particularly associated with the partly imperfect quality of the seal and the difficulty to control process parameters influencing the quality of the seal, sealing clamp systems have been adopted (as exemplified in EP1459725A1). The aim of such systems was to improve the fluid injection phase in order to reach the maximum volume available in the overlap of the body parts while the capsule remains free of residual liquid on its surface. The above has been achieved by implementing a rotating clamp to maintain the capsule in an upright position when a sealing liquid is injected.
Although the above described state of the art equipment and methods have shown some incremental successes in overall sealing of hard capsules, they are yet unsuitable for processing (e.g. sealing) in aseptic applications.
Thus, there still remains a need for an apparatus and method that specifically and effectively enable aseptic sealing of hard capsules, particularly for example in biological/bacterial liquid filling of capsules.